Royal protocol at the Princess Grace Foundation gala was strictly observed by many who wanted to get close to Princess Caroline of Hanover. A spy reports, “Guests in her immediate vicinity were told to bow, that you are not allowed to reach for her hand unless she reaches for yours, and that you cannot leave before her.” All these rules made for some formal behavior, except for the night’s honoree, Denzel Washington, who was seated next to the princess at Cipriani 42nd street last week. “He seemed pretty relaxed and at one point even spent some time texting on his phone,” our spy added. Denzel’s rep didn’t get back to us. Other guests included Debbie Bancroft and jeweler Jeffrey Rackover.